WilberM3 wrote: anybody have any experience with how the location of a muffler in a system would affect sound/performance? like if you ran a straight pipe with a muffler under the middle vs. right at the rear bumper?

I think that muffler placement effect tone. I think that might be it. If I recall, the HAMB said that closer to the collector = more rap to the sound.

1). Top Fuel dragsters make awesome pictures.

2). They don't have any backpressure and make retarded amounts of power and competition is such that if adding backpressure made more power, they would.

3). I am not an expert and am mostly using this to post this picture.

Appleseed wrote: I think that muffler placement effect tone. I think that might be it. If I recall, the HAMB said that closer to the collector = more rap to the sound.

Move the muffler back until you just start to hear country.

SkinnyG wrote:

Appleseed wrote: I think that muffler placement effect tone. I think that might be it. If I recall, the HAMB said that closer to the collector = more rap to the sound.

Move the muffler back until you just start to hear country.

But I don't have a truck with an 8 foot bed to put the muffler that far back

thatsnowinnebago wrote: #1). Top Fuel dragsters make awesome pictures. #2). They don't have any backpressure and make retarded amounts of power and competition is such that if adding backpressure made more power, they would. #3). I am not an expert and am mostly using this to post this picture.

Top fuel dragsters play by a different set of rules.

They burn the electrodes off their spark plugs within a matter of seconds, and just detonate down the drag strip the whole way.

mad_machine wrote:

SkinnyG wrote:

Appleseed wrote: I think that muffler placement effect tone. I think that might be it. If I recall, the HAMB said that closer to the collector = more rap to the sound.

Move the muffler back until you just start to hear country.

But I don't have a truck with an 8 foot bed to put the muffler that far back

Can you move it far enough back to at least get rockabilly? A short box might be all you need for that. Preferably black. With flames.

tuna55 wrote: I am just going to follow you around and tell you you're right all of the time, apparently.

Ooo, I need one of those.

I'd check old issues of Hot Rod or Car Craft for details. Those guys do test pretty well, and I'm sure they've hit this up in the past.

WilberM3 wrote: anybody have any experience with how the location of a muffler in a system would affect sound/performance? like if you ran a straight pipe with a muffler under the middle vs. right at the rear bumper?

closer to the front tends to mean that there is more unbaffled length of tailpipe in which more noise can be parasitically induced by the pulses in the pipe.

The school of thought is that the closer you put it to the outlet, the better for power and sound removal. The thought is that exhaust temps drop drastically as they pass through the tubing, therefore the density increases and the CFMs reduce proportionally. Therefore a muffler that restricts flow a little at the back would theoretically restrict flow a tad more up closer to the front.

What seems to make an all-around good compromise is the use of resonators. Use a high-flowing muffler up in the middle, then another high-flowing resonator in the back. The thought there is that you're splitting up the sound deadening over two free-flowing mufflers instead of one more restrictive piece.

unevolved wrote:

thatsnowinnebago wrote: #1). Top Fuel dragsters make awesome pictures. #2). They don't have any backpressure and make retarded amounts of power and competition is such that if adding backpressure made more power, they would. #3). I am not an expert and am mostly using this to post this picture.

Top fuel dragsters play by a different set of rules. They burn the electrodes off their spark plugs within a matter of seconds, and just detonate down the drag strip the whole way.

Like I said, I'm no expert

unevolved wrote:

thatsnowinnebago wrote: #1). Top Fuel dragsters make awesome pictures. #2). They don't have any backpressure and make retarded amounts of power and competition is such that if adding backpressure made more power, they would. #3). I am not an expert and am mostly using this to post this picture.

Top fuel dragsters play by a different set of rules. They burn the electrodes off their spark plugs within a matter of seconds, and just detonate down the drag strip the whole way.

Yep, they basically run like a diesel, so I guess the diesel rules apply.

Scaviging exhaust properly has to do with proper tubing sizing. Bigger isnt always better. There is an optmum intake speed and a optimum exhaust speed. On the exhaust side it starts out fast and hot and wants to expand. Turbos realy like big piping right out of the exducer. As the gasses cool the expansion and speed reduce so to keep the proper speed as it cools piping size needs to be reduced as it reaches the rear. Thats like the smaller muffler at the rear reduces power if moved to the front. Turbo systems sometimes need back pressure in the system. Less so with a good blow off / by-pass system. When designing a turbo set up we would decide on a desired back pressure. This was to keep the turbo from over speeding and going into surg. This basicly kept the system within the best efficency range baised on the compressor and turbine mapping.

If you pick your turbine wheel/housing right you don't have to worry about post turbo back pressure. Just watch turbine inlet pressure vs boost...

Anyway in all the dynos I've done on 2-3L engines I've never seen a drop in hp or torque from going to a 'reasonably large exhaust' even 3" on a little 2L didn't lose a thing down low but it did sound interesting.

I'm of the 'after collector, as little back pressure as you can get'

This thread needs more Andy Nelson and fewer references to Top Fuel since it's pretty much worthless from a "streetable" standpoint on power production. Never mind all the little technical details that make these machines curious.

Keep the tubes just small enough so exhaust pulses don't fall in on themselves and result in reversion, that's my thought.

Just depends on what your going for. Gurny Eagle Indy engines I did turbo stuff for in the late 70's early 80's were a different set up than a factory set up. The main thing with over speeding other than efficency loss is the higher speed destroys the bearings. Turbos back in the 70s and todays speeds have changed too. Back in 1980 35000 RPMto 45000 RPM was concidered high speed today they have some that turn over 120000 RPM. Back in 69 I invented the adjustable waist gate for the Gurney Indy cars. In the late 80s I invented the first sucsessful variable geometry turbine HSG which broadened the turbine map.

What more can i add

http://www.youtube.com/watch?v=XzO7OfyqSTY

http://www.youtube.com/watch?v=5jDhhEHcVvQ